Thursday, October 1, 2015

Calculus: Early Transcendentals, Chapter 7, 7.1, Section 7.1, Problem 22

You need to use integration by parts, such that:

int udv = uv - int v du
u = (arcsin^2(x))=> du = (2arcsin x)/(sqrt(1-x^2))dx
dv = 1 => v = x
int (arcsin^2(x)) dx = x*(arcsin^2(x)) - 2 int arcsin x*x/(sqrt(1-x^2))dx
You need to solve the integral int arcsin x*(x/(sqrt(1-x^2)))dx using substitution arcsin x= t , such that:
arcsin x = t => (dx)/(sqrt(1-x^2))= dt
int arcsin x*(x/(sqrt(1-x^2)))dx = int t*sin t dt
You need to use integration by parts to solve int t*sin t dt , such that:
u = t => du = dt
dv = sin t => v = -cos t
int t*sin t dt = -t*cos t + int cos t dt
int t*sin t dt = -t*cos t + sint + c
Replacing back the variable yields:
int arcsin x*(x/(sqrt(1-x^2)))dx = -arcsin x*cos(arcsin x) + x + c
int (arcsin^2(x)) dx = x*(arcsin^2(x)) - 2( -arcsin x*cos(arcsin x) + x) + C
int (arcsin^2(x)) dx = x*(arcsin^2(x)) + 2arcsin x*cos(arcsin x) - 2x + c
Hence, evaluating the indefinite integral, using parts and substitution, yields int (arcsin^2(x)) dx = x*(arcsin^2(x)) + 2arcsin x*cos(arcsin x) - 2x + c.

No comments:

Post a Comment

Why is the fact that the Americans are helping the Russians important?

In the late author Tom Clancy’s first novel, The Hunt for Red October, the assistance rendered to the Russians by the United States is impor...